Coated welding rod



Patented Get. 19, 1948 COATED WELDING ROD No Drawing. Application January 28, 1946, Serial Noi5643,971. In the Netherlands December 15, 19

Claims. (Cl. 2198) Nl'iED STAT This invention relates to coated welding rods which permit of electric arc-Welding in such fore the whole of the welding rod is consumed, since such a use of a welding rod has nothing to manner that when the work-piece is touched by do with a method of manufacturing welding rods. the welding rod, the ignition of the arc may take The invention is of particular importance for place without any further expedients. We mean electric arc-welding by the touch-welding thereby that the welder has no need to perform a method, which is facilitated by it. In view thereparticular manipulation such as tapping, to initiof it is an obvious fact that the welding rods ate the welding process so that the welding rods adapted for use of the invention also include may be considered to be of the self-starting type. welding rods which permit of touch-welding. In With self-starting rods, a current is passed on 10 this case the coating must not only be suitable to touching the work-piece, which current has such a value that the starting of the arc occurs almost by means of melting or sintering at the extremity immediately thereafter, the melting-off process thus starting of its own accord.

The present invention is based on the recognition of the fact that with several coated Welding rods of the kind wherein the coating mass has the property that preliminary melting or sintering raises the conductivity thereof for electric current to such an extent that an extremity of such a coated welding rod which has thus been treated beforehand is sufiicient to make the rod self-starting. It is thus readily possible to select which comprises the steps of coating a metal core experimentally the welding rods that are suitable with semi-conductive slag-forming material havfor use according to the invention. The presence mg a constituent which is more conductive after of a fairly large quantity of semi-conductive fusing and heating the welding and of the coating material or of a metal, such as F6304 or Fe, in the to a high temperature for a short time to fuse coating adds to the suitability for use of the insaid constituent and so convert the semi-conventicn, since the amount of such a material is ductive material at the said end portion into a in this case of influence. conductive portion.

According to the present invention, such coated 2. A method of providing a self-starting weldwelding rods are made self-starting by submitting ing rod for electric arc-welding, which comprises the extremity intended for the formation of arc the steps of coating a metal core with a semi- ;o a thermal treatment which locally brings about sintering or fusion of the coating mass. and heating an extremity of the rod for a short As compared with entirely difierent methods )f making the welding extremity of a coated velding rod to melt on" automatically, such as by said end portion into a conductive portion. flaking it terminate in a et p, 0 y p o- 3. A coated electric arc-welding rod, comprisid n a little conductive cap, the invention offers 40 ing a semi-conductive slag-forming coating havhe advantage of a cheaper manufacture. ing a fusible metallic constituent dispersed The present invention may be real sed by heattherein, the portion of said coating at the welding 1g the extremity of the rod for a short time to extremity being in a fused form and so having a hi h t mp a re, f r ex mpl with the aid of a greater conductivity than the portion of the ydrogenoxygen flame, o l ed by oo g. The coating remote from said welding extremity.

ing rod to bear on the edge of the cup. A welding rod according to this particular form of construction lends itself to being used in an automatic device.

What we claim is:

1. In the manufacture of a self-starting welding rod for electric arc-welding, the method so convert the semi-conductive coating at the item oject of the present invention may also be atiined by a formation of an arc of short duration. urthermore, the heating of the welding extremy according to the invention may take place by re high-frequency method.

It is evident that the present invention has no ference to the ordinary manipulations of the elder, during which it occurs, even with welding d's adapted for use of the invention, that during e welding operation the arc is interrupted be- 4. A coated touch electric arc-welding rod, comprising a metal core and a semi-conductive coating having Fe304 dispersed therein, said coating being locally fused at the welding extremity to form a metallic tip and having a greater conductivity than the portion of the coating remote from said welding extremity.

5. A coated alternating current touch welding rod comprising a metal core and a semi-conductive coating having iron dispersed therein, said coating being locally fused at the welding ex- REFERENCES CITED tremity of the coating to form a. metallic tip 1 having a. greater conductivity than the portion g g s g ggf fifi are of record n the of the coating remote from said welding ex- 'tremity. 5 UNITED STATES PATENTS HENRI BIENFAIT- Number Name Date PAUL CHRISTIAAN vm mm WIL EN- 2,370,100 White Feb. 20, 1945 

